1. Field of the Invention
The present invention is directed to a replaceable ductile fuse, and in particular, to a replaceable ductile fuse configured to be positioned in the load path between an anchor preferably partially embedded in concrete and a structure.
2. Description of Related Art
Structural elements, such as a building column, are commonly joined to a supporting concrete foundation with an anchor that is partially embedded in the concrete and coupled to the structural element. In the case of a building column, the column may have a baseplate with an opening that receives a portion of the anchor. A nut may be threaded on the anchor to clamp the baseplate between the nut and concrete foundation.
The American Concrete Institute's Building Code Requirements for Structural Concrete (ACI 318) specifies certain requirements for the connection between a structural element and a concrete anchor, including seismic design requirements that are applicable when the structure is located in an area that may be subject to seismic loads. Designing the connection so that it deforms in a ductile manner is in part at least one way to satisfy the seismic design requirements.
One current technique for designing such a connection so that it satisfies the seismic design requirements of ACI 318 includes designing the anchor rod so that it fails in a ductile manner before failure of the concrete within which the rod is embedded. After the anchor rod fails, however, it is costly and time-consuming to replace the anchor rod. Other techniques include adding concrete reinforcing steel which is developed on both sides of the concrete breakout cone thereby making the tensile failure model no longer dependent upon concrete failure modes, or overdesigning the connection by a certain percentage. These techniques, however, may be costly and time-consuming to implement.